Compositions, including silicon-based adhesive compositions, for bonding rubber to metal and other substrates are well known in the art.
In the search for the ideal all-purpose adhesive there have been developed a variety of adhesive compositions which have been utilized with varying degrees of success in bonding elastomeric materials to themselves or to other substrates such as metal substrates. As a general rule, the known adhesives which have been effective as simple rubber-to-metal bonding agents are limited with respect to the type of elastomer to be bonded. That is to say, an adhesive which is capable of providing an acceptable bond with butadiene/styrene elastomers may be unsatisfactory with ethylene/propylene/ nonconjugated diene terpolymer (EPDM) elastomer or polyisobutylene/ isoprene elastomer.
In addition to the problem of lack of versatility prior art adhesive compositions, including silicon-based adhesives, tend to suffer from one or more other disadvantages, including a general inability to afford optimum adhesion, particularly at elevated service temperatures; poor storage stability at room and/or elevated temperatures; poor resistance to prebake. Moreover, the resistance of the adhesive bond to environmental conditions such as oils, solvents and moisture is often poorer than normally desired in many commercial applications. Thus, there remains a need for more effective silicon-based adhesive formulations which can be employed in the bonding of various elastomeric materials to substrates such as metal and which exhibit an adhesive bond of improved resistance to degradation from environmental factors.
It is an object of the invention to provide adhesive compositions for bonding a variety of elastomers to various substrates, particularly metal substrates.
Another object of the invention is to provide adhesive compositions which afford strong elastomer-substrate adhesive bonds which exhibit high environmental resistance.